Field of the Disclosure
The disclosure relates to the field of OLED display technology, more particularly, to an OLED display panel and a manufacturing method thereof.
Description of the Related Art
OLED (organic light-emitting diode) has been widely used in digital products due to its features like lightweight and power saving. OLED display technology is different compared with the traditional LCD (liquid crystal display) display mode; OLED display technology needs no backlight and uses very thin organic material coating and glass substrate; the organic materials will shine when electric current passes through. As a display device, the OLED display screen may also be affected by environmental factors; especially in a strong light environment, the display effect of the OLED display screen will also decline.
The OLED controls the output current mainly through a TFT (thin-film transistor), to display different brightness; a structure of the TFT-OLED is as shown in FIG. 1.
Brightness of the OLED with low gray-scale is very low, if brightness of 255 gray-scales is 250 nits, then brightness of 20 gray-scales is about 1 nit, and the corresponding brightness of the sub-pixels of red light and green light is only tens of nits, brightness of sub-pixels of blue light is only about single-digit nits; and the electric current needed by sub-pixels is 10−10−11 A, yet off-state leakage current of the TFT is also within the range, therefore the leakage current of the TFT may lighten the OLED and cause the OLED to shine slightly in a black picture; on the other hand, since a certain amount of step voltage still exists in the OLED with a low gray-scale; if cut-in voltage of sub-pixels of R, G and B is different, then pixels with the lowest cut-in voltage is the easiest to be lightened, thus color cast is easy to occur in a low gray-scale.
Therefore, to improve the low gray-scale color cast of the OLED panel, on one hand we should reduce the leakage current of the TFT; on the other hand we should reduce current density of the OLED under low voltage; thus a new technical solution to overcome the above-mentioned technical problems becomes a direction for those skilled in the art to be dedicated to.